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"The Big Bang Theory" production start is in limbo as contract negotiations with the original cast stall. Stars Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg and Kunal Nayyar still have no deals to return to the show, two weeks before the scheduled start date for the production on season 8 on July 30.

Sources say the two sides are still far apart and there has been no movement in the negotiations, which began in September last year. The five actors seek hefty pay raises after their co-stars Mayim Bialik and Melissa Rauch inked new deals that gave them substantial salary increases.

Back in September, it was reported that Parsons, Galecki and Cuoco would negotiate together and asked for up to $1 million an episode from their current salary of $325,000 per episode. Helberg and Nayyar also negotiated together.

A similar situation also happened in 2010, when Parsons, Galecki, Cuoco, Helberg and Nayyar were in the midst of talks with producing studio Warner Bros. TV while nearing the start of production. However, at that time they had existing contracts and were obligated to show up for work, so they continued the negotiations for pay bumps while filming the show.

Sources tell The Hollywood Reporter that the studio is confident a deal will be reached before season eight begins and the cast will show up for work on the show's Burbank set at the end of the month, regardless of whether or not they have new contracts.

"The Big Bang Theory" has been renewed through season 10 by CBS.